浙江省海岸侵蚀及防治概述

Coastal erosion and prevention in Zhejiang Province

浙江海岸侵蚀现象普遍存在。基岩海岸海蚀地貌发育,因其组成物质抗冲蚀能力强,岸线后退不明显;砂砾质海岸普遍发生侵蚀,尤其是无计划的人工挖沙,造成沙滩减小或消失;淤泥质海岸大多处于缓慢的淤涨状态,但由于自然条件的改变和人为作用的影响,某些岸段发生侵蚀,特别是受到台风暴潮的影响,岸线在短时间内出现大规模后退和滩面下蚀。侵蚀岸段主要见于杭州湾北岸澉浦至金丝娘桥岸段,杭州湾南岸临山至西三岸段及瓯江口北岸盘石至黄华岸段。淤泥质海岸后缘为滨海平原,组成物质为粘土质粉砂,抗冲蚀能力弱,为防止和减轻海岸侵蚀,沿岸建造各类海岸工程(海塘、丁坝、导堤等),提高防潮抗浪能力,在朝滩种植大米草,互花米草,消浪促淤明显。另外,在海岸开发活动中,应加强海岸侵蚀监测和综合管理。

Erosion occurs along the coastal zone of Zhejiang Province. Erosional morphology is well-developed along the rocky coast. It is stronger against eroded action by tides and waves. Therefore, the coastline does not retreat obviously along the rocky coast. Erosion is present all over the sandy coast, resulting in beach reduction and disappearace, especially owing to excavation of sand. Usually, advance slow state is dominant along the silt and muddy coast, but erosion is present in some segments due to the change of nature condition and human impact. During the period of typhoon and surgetide, the coastline retreats obviously and the tidal flats are eroded. Erosional segments are mainly following areas: north bank of the Hangzhou Bay from Ganpu to Jingsiniangjiao; south bank of the Hangzhou Bay from Xisan to Lingsan and north bank of the Oujiang Estuary from Panshi to Wanghan. The silt and muddy coast consists of clayey silt and is connected by the plain towards the land. Therefore, ability of prevention against tides and waves is weak. In order to prevent and reduce eroded action along the coast, dyke, spur and jetty have been built in the coastal zone, enhancing ability to prevent against tides and waves. Spartina anghica and Spartina alternifloro have been planted in the tidal flats to help siltation and weaken greatly wave action on the coastal zone. In addition, it should be enhanced to monitor eroded action and to coordinate development activities of the different branches in the coastal zone.